I know my storage bags aren't leaking!! I'm losing my mind

So I'm trying to build up my stash for when I go back to work. I'm pumping say 5 oz bottles and putting them in the freezer bags, but when I pull them out to use them, thaw them and put the milk in a bottle it measures out to like 4 oz. I know they lose some nutritional value when frozen but an ounce? My bags aren't leaking, I know that...I've even double bagged them to make sure. Anyone know what's up. I feel like it's an uphill battle I'm not producing that much so any milk lost is not making me happy.

***also after doing some research it looks like I might have excess lipase. Could that be a cause? Baby doesn't have any issues with BF or taking a bottle...

Re: I know my storage bags aren't leaking!! I'm losing my mi

Welcome to the forum!

So, when you pump, are you pumping into the same brand of bottle that you're pouring the bags into at the end of the process? Often one brand of bottle will have different oz markings than another, and that could explain the apparent difference in volume. A good way to test this would be to pour 5 oz of water from your pump bottle into your feeding bottle, and see if this is all due to differences in the markings on the sides of the bottles.

If you're using the same brand of bottle all the way through, then here are some alternative possibilities to explain the loss of volume:
- When milk is freshly pumped, it's often a bit frothy. Once milk has been sitting for a while, the froth dissipates, making the volume look smaller.
- Pouring milk from bottle to bag to bottle probably leaves some milk clinging to the sides of the bottle/bag. It's generally not much, but it could be enough to be noticeable.
- Sublimation during freezer storage could cause the milk to lose some of its water volume. (Sublimation is the process by which a solid turns into a gas without passing through a liquid phase- like when dry ice turns into has without becoming liquid. Basically, it's freezer burn.)

When we talk about milk losing nutritional value during storage, we're not talking about a loss of volume. Instead, what we're talking about is a breakdown of some of the more fragile components of the milk. It is not known how much of a problem this problem is- it's more of a hypothetical than anything else! And lipase doesn't destroy your milk. It simply breaks down the milk fats into smaller components. This would actually be helpful if it was happening inside the baby's digestive system. But when it happens in storage, it can cause taste issues that make some babies unwilling to drink stored milk.

Re: I know my storage bags aren't leaking!! I'm losing my mi

They are different brands...madela pump and Lansinoh bags. I did test out the different brand different ounce theory last week figuring that's what it was but I confirmed they both match up. When I put he pumped milk in the bags (typically a couple pumping sessions, so they've been in the fridge for a couple hours) they aren't frothy at all. I've put the milk from the pumped bottle into the bottle were using to feed him and they match up...so the milks going somewhere in the freezer!! Lol hmmm...

Re: I know my storage bags aren't leaking!! I'm losing my mi

I know you said that they matched up but what did you compare? My 5oz medela bottles overestimate and so do my Lansinoh bags. I actually use the 2.5 oz Medela bottles for measuring as the taller, skinnier bottle should give you a more accurate measurement. If you have one of those, I would measure out the amount with that bottle, then pour into a bag, and then go to the bottle you feed with. You can do this whole thing with water to compare how the amount looks in each bottle/bag and how much you might lose in the transfer. Also, could you freeze some milk in a bottle and then thaw and see if any of the milk disappeared? If not, maybe it is a bag issue.

Hopefully you can figure this weird situation out and account for that missing milk.

Re: I know my storage bags aren't leaking!! I'm losing my mi

I had the same issue till I realized my Ameda pumping bottles overestimate. So now I know to fill it up a bit over the line and that's accurate according to the Avent bottles he drinks from. The bag measurements are completely inaccurate because it depends on how much air you have in the bag when sealing it shut. I can pour in 2 oz and squeeze out the air and it can come up to the 4oz line even! Best way to measure is to use a kitchen scale. My bags way .25 ounces so if a filled bag is 4.25 oz or so, I know there's a real 4 oz in there.

Re: I know my storage bags aren't leaking!! I'm losing my mi

I had the same problem but it was like everyone said, the difference was that the measurement markings were nit the same on my pump bottles, storage bags and the feeding bottles. They were all different!! You would think that 4 oz is 4 oz but it was different on my Hygeia pump bottles, Lansinoh bags and my Avent bottles. Good luck! There is nothing more frustrating that losing milk!